The global system for mobile communications (GSM) is the most widely used wireless communication system in the world and the number of users of the system is still increasing.
FIG. 1 shows an architecture of a traditional GSM system. In the architecture, an Abis interface is used between a base station controller (BSC) and a base transceiver station (BTS). FIG. 2 shows the structure of the Abis interface. In the prior art, the Abis interface is over a time division multiplex (TDM) network. Voice and packet data is generated as TRAU frames according to the 3rd Generation Partner Project (3GPP) protocol. A TRAU frame includes payload data bits, synchronization bits required in TDM mode, control bits, and padding bits for the normative frame structure.
Considering the wide deployment of IP networks, change of traffic models, network convergence, and transmission bearer cost, the traffic on the Abis interface needs to be carried over an IP packet network. When the traffic on the Abis interface is carried over an IP packet network, the following problems need to be solved: the packet network has different features from the TDM network, such as delay, jitter, and packet loss.